CHORD ELECTRONICS Hugo Portable DAC/Headphone Amplifier with Bluetooth Black

Design and Technical Highlights

The Enabling Technologies

In the legendary Chord Electronics DAC 64, Rob Watts, Chord’s brilliant DAC designer, used (4x) 100,000 gate logic arrays FPGAs. Each needed about eight watts of power at precisely 3.3 volts. These power-hungry monster chips meant that the DAC 64 sometimes ran warm: 38 degrees above ambient. This was never a problem for the design, as Chord had accounted for it and carefully managed the thermal gradients across the circuits. However, the high temperature determined that with that early generation of Xilinx chips, they could never be considered for use in a
mobile product, as it would have a battery life of just a few seconds! However, twenty years of Moore’s Law has increased the available gate-count in present-generation chips to levels that could not have been imagined at the time of the DAC 64's development, two decades ago.
Also of significance, is the dramatically reduced voltage at which these new Xilinx chips can run: less than 0.7 volts. These factors have reduced the power requirement in Hugo's design to infinitesimally small values in comparison. Xilinx have stopped using gate-count to estimate chip sizes; needless to say that we are now not constrained by the amount of electronics that we have been able to pack into the new Hugo design, all of which is required for the greatly improved performance and functionality that Hugo can offer.

Technical Highlights

To get the highest power efficiency to prevent excessive battery drain, ultra-efficient switching regulators have been used. Sound quality issues - due to the switching noise - have been completely avoided by virtue of using cleverly designed 1.2MHz switching regulators in conjunction with very careful RF filtering and circuit layout. Indeed, signal-related power draw has been reduced with this technique and coupled with the low-power Xilinx Spartan-6 chip we are using, has led to clearly measured, dramatic performance improvements. Crosstalk, due to ground plane signal-induced PSU injection, has been totally eliminated, giving a wonderful smooth sound quality.
Hugo has an astounding 26,368 digital tap WTA filter. This advanced feature gives much better soundstaging, instrument separation and timing. This is the most Chord Electronics has ever put into one of its products and is exceptional when compared to typical industrial DAC chips that typically have around 256. This demonstrates the absolute technical superiority of this new design collaboration with Rob Watts.
(A white paper fully explaining these complex timing issues will be available at a later date).
Hugo's discrete and very high-speed analogue amplifier headphone output stages give exceptionally low distortion of around -140 dBV, plus they have an astounding ability to drive happily into 8 ohm loads. This gives Hugo not only the ability to drive three pairs of low-impedance 30 Ohm headphones simultaneously, but also ordinary loudspeakers. Additionally, Hugo's large amplified output voltage swing means that high-impedance 300 Ohm headphone types can be driven at 110 SPL without difficulty.
One measure of Hugo's vast and complex internal structure is that Hugo has 16 custom-designed DSP cores running at 208 MHz to implement the WTA (Watts Transient Aligned) filtering. Hugo also has new and improved noise-shaper architecture on the 4e pulse-array DAC: this gives an utterly convincing pure tonal soundscape with far better depth.

Hugo Input Details

- A high-speed optical
- RCA (pair)
- A micro USB (which does not need driver software and is for use with all Apple and Android phones/tablets, and takes absolutely no power from the partnering product as they do not allow this.)
- A second HD micro USB input, an ultra-high-speed input, requires both driver software (for Windows, others TBC) which is Chord-supplied, and also a small amount of power over the USB. Therefore, this ultra-high-data-rate input is for use with laptops and players for playing high-definition DXD files: DSD 128 and PCM to 384 kHz.
- An A2DP Bluetooth link (for use if a wired link is not available), including the most advanced audio coding known as aptX: this music encoding is available from all Android products. Hugo has been designed featuring our in-house developed branded Chord Bluetooth module for truly great sound quality.
Hugo outputs in detail
Hugo has one full-sized headphone jack socket and two mini jacks. Chord has also included a pair of RCA outputs for use with larger static audio systems. Hugo's battery life is up to an impressive fourteen hours! – that's enough even for the most avid listener who's on the longest of flights. Additionally, Chord has included attractive and intelligent lighting features that show the frequency of the file data source, plus the same for the digital volume control, which is an advanced design that does not lose data bits at lower volume levels, thereby maintaining the music signal’s reference-class integrity.
An optional advanced all-digital psycho-acoustic delay and crossfeed DSP cored codec has been included should the listener wish to experience a truly realistic out-of-head stereo musical experience.

Outputs

Inputs

Inputs

- Optical TOSLink 24-bit/192KHz-capable
- RCA coaxial input 24-bit/384KHz-capable
- Driverless USB input 16-bit/48 kHz-capable (designed for tablets/phones)
- HD USB input 32-bit/384KHz and DSD128-capable (designed for computer/laptop playback; requires driver installation for Windows, others TBC.

Outputs

- 2x3.5mm headphone jacks
- 1x6.35mm (1/4 inch) headphone jack
- 1x (pair) stereo RCA phono output

Technical Specs

- Advanced digital volume control
- Crossfeed filter network
- Battery powered for approximately 14 hours operation. The batteries are small and less than 20Ah so this means no shipping restrictions which can be found with other less efficient designs using larger batteries.
- Input, sample rate and volume level indication by colour-change LEDs
- 26K tap-length filter (more than double when compared to the QuteHD DAC)
- THD: 140dB
- Headphone output: 110dB SPL into a 300ohm headphone load